The present invention relates to a copy-guard system for determining whether multimedia data recorded on a recording medium is original or copied and then preventing the data from being copied illegally when it is not original.
The present invention also relates to an information recording medium used in the above copy-guard system.
In a digital recording medium such as a DAT (Digital Audio Tape) and an MD (Mini Disc), a digital copy of the original can be made only once but a copy of the copied data (secondary copy) cannot be made again. This is called a CGMS (Copy Generation Management System) or an SCMS (Single Copy Management System). In these systems, a two-bit flag indicates whether data has been copied or not (data can be copied or not).
However, they have a problem in which data is likely to be altered and copied illegally during its transmission or a so-called pirated medium is likely to circulate.
Consequently, the conventional copy-guard system has such a problem as described above.
The present invention has been developed in consideration of the above situation, and its object is to provide a copy-guard system for preventing an unauthorized copy based on identification information which represents whether the contents recorded on an information recording medium are the original or not and which is recorded in an error-correction code.
Another object of the present invention is to provide an information recording medium used in the above copy-guard system.
In order to attain the above objects, according to a first aspect of the present invention, there is provided a copy-guard system comprising:
first decoding means for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded;
encoded digital data acquisition means for acquiring digital data encoded by error-correcting the digital data decoded by the first decoding means;
detection means for detecting an error position and an error symbol value of the encoded digital data acquired by the encoded digital data acquisition means;
identification information detection means for replacing the digital data encoded and error-correction-coded with part of the digital data encoded and error-correction-coded, based on the error position and the error symbol value detected by the detection means and then recording the part of the digital data thereby to detect identification information representing whether the information recording medium is original or copied;
first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means; and
copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.
According to a second aspect of the present invention, there is provided a copy-guard system comprising:
first decoding means for decoding digital data, which is encoded and error-correction-coded by a product code, from an information recording medium in which key information encoded for the digital data is recorded;
first acquisition means for acquiring digital data encoded and error-correction-coded by an inner code when the digital data decoded by the first decoding means is error-corrected by an outer code;
detection means for detecting an error position and an error symbol value of the digital data acquired by the first acquisition means;
identification information detection means for replacing the digital data encoded and error-correction-coded by the inner code with part of the digital data encoded and error-correction-coded by the inner code, based on the error position and the error symbol value detected by the detection means and then recording the part of the digital data thereby to detect identification information representing whether the information recording medium is original or copied;
first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means; and
copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.
According to a third aspect of the present invention, there is provided a copy-guard system comprising:
first decoding means for decoding digital data, which is encoded and error-correction-coded by a product code, from an information recording medium in which key information encoded for the digital data is recorded;
first acquisition means for acquiring digital data encoded and error-correction-coded by an inner code when the digital data decoded by the first decoding means is error-corrected by an outer code;
first detection means for detecting a first error position and a first error symbol value of the digital data acquired by the first acquisition means;
second acquisition means for acquiring digital data encoded by error-correcting the digital data, which is acquired by the first acquisition means, by the inner code;
second detection means for detecting a second error position and a second error symbol value of the encoded digital data acquired by the second acquisition means;
identification information detection means for replacing the digital data encoded and error-correction-coded with part of the digital data encoded and error-correction-coded by the product code, based on the first error position and the first error symbol value detected by the first detection means and the second error position and the second error symbol value detected by the second detection means, and then recording the part of the digital data thereby to detect identification information representing whether the information recording medium is original or copied;
first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means; and
copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means. According
According to a fourth aspect of the present invention, there is provided a copy-guard system comprising:
first decoding means for decoding digital data, which is encoded and error-correction-coded by a product code, from an information recording medium in which key information encoded for the digital data is recorded;
identification information detection means for replacing the digital data with part of the digital data and then recording the part of the digital data, thereby to detect identification information of the digital data decoded by the first decoding means, based on a pattern of identification information representing whether the information recording medium is original or copied;
first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means; and
copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.
According to a fifth aspect of the present invention, there is provided a copy-guard system comprising:
first decoding means for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded;
encoded digital data acquisition means for acquiring digital data encoded by error-correcting the digital data decoded by the first decoding means;
detection means for detecting an error position and an error symbol value of the encoded digital data acquired by the encoded digital data acquisition means;
second decoding means for decoding the digital data acquired by the encoded digital data acquisition means;
extraction means for extracting positional information of identification information, which is embedded in the digital data decoded by the second decoding means, as watermark data;
identification information detection means for replacing the digital data encoded and error-correction-coded with part of the digital data encoded and error-correction-coded, based on the error position and the error symbol value detected by the detection means and the positional information of the identification information extracted by the extraction means, and then recording the part of the digital data thereby to detect identification information representing whether the information recording medium is original or copied;
determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means; and
copy protection means for protecting a copy of the information recording medium based on determination results of the determination means.
According to a sixth aspect of the present invention, there is provided a copy-guard system comprising:
decoding means for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded;
encoded digital data acquisition means for acquiring digital data encoded by error-correcting the digital data decoded by the decoding means;
detection means for detecting an error position and an error symbol value of the encoded digital data acquired by the encoded digital data acquisition means;
compression means for compressing the key information encoded and stored in the information recording medium;
extraction means for extracting identification information, based on the key information compressed by the compression means and the error position and the error symbol value detected by the detection means;
determination means for determining whether a copy of the information recording medium is protected based on the identification information extracted by the extraction means; and
copy protection means for protecting a copy of the information recording medium based on determination results of the determination means.
According to a seventh aspect of the present invention, there is provided a computer program product for operating a computer, the computer program product comprising:
a computer readable medium;
digital data encoded and error-correction coded, the digital data including identification information which is replaced with part of the digital data and recorded and which represents whether the computer readable medium is original or copied; and
key information encoded for the digital data encoded and error-correction-coded,
wherein each of the digital data and the encoded key information is recorded on the computer readable medium in executable form and loadable into the computer for execution by a processor.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.